export let WebRtcStreamer = (function () {
  /**
   * Interface with WebRTC-streamer API
   * @constructor
   * @param {string} videoElement - id of the video element tag
   * @param {string} srvurl -  url of webrtc-streamer (default is current location)
   */
  let WebRtcStreamer = function WebRtcStreamer(videoElement, srvurl) {
    if (typeof videoElement === "string") {
      this.videoElement = document.getElementById(videoElement);
    } else {
      this.videoElement = videoElement;
    }
    this.srvurl = srvurl || location.protocol + "//" + window.location.hostname + ":" + window.location.port;
    this.pc = null;

    this.mediaConstraints = { offerToReceiveAudio: true, offerToReceiveVideo: true };

    this.iceServers = null;
    this.earlyCandidates = [];
  };

  WebRtcStreamer.prototype._handleHttpErrors = function (response) {
    if (!response.ok) {
      throw Error(response.statusText);
    }
    return response;
  };

  /**
   * Connect a WebRTC Stream to videoElement
   * @param {string} videourl - id of WebRTC video stream
   * @param {string} audiourl - id of WebRTC audio stream
   * @param {string} options -  options of WebRTC call
   * @param {string} stream  -  local stream to send
   */
  WebRtcStreamer.prototype.connect = function (videourl, audiourl, options, localstream) {
    this.disconnect();

    // getIceServers is not already received
    if (!this.iceServers) {
      console.log("Get IceServers");

      fetch(this.srvurl + "/api/getIceServers")
        .then(this._handleHttpErrors)
        .then(response => response.json())
        .then(response => this.onReceiveGetIceServers(response, videourl, audiourl, options, localstream))
        .catch(error => this.onError("getIceServers " + error));
    } else {
      this.onReceiveGetIceServers(this.iceServers, videourl, audiourl, options, localstream);
    }
  };

  /**
   * Disconnect a WebRTC Stream and clear videoElement source
   */
  WebRtcStreamer.prototype.disconnect = function () {
    if (this.videoElement?.srcObject) {
      this.videoElement.srcObject.getTracks().forEach(track => {
        track.stop();
        this.videoElement.srcObject.removeTrack(track);
      });
    }
    if (this.pc) {
      fetch(this.srvurl + "/api/hangup?peerid=" + this.pc.peerid)
        .then(this._handleHttpErrors)
        .catch(error => this.onError("hangup " + error));
      try {
        this.pc.close();
      } catch (e) {
        console.log("Failure close peer connection:" + e);
      }
      this.pc = null;
    }
  };

  /*
   * GetIceServers callback
   */
  WebRtcStreamer.prototype.onReceiveGetIceServers = function (iceServers, videourl, audiourl, options, stream) {
    this.iceServers = iceServers;
    this.pcConfig = iceServers || { iceServers: [] };
    try {
      this.createPeerConnection();

      let callurl = this.srvurl + "/api/call?peerid=" + this.pc.peerid + "&url=" + encodeURIComponent(videourl);
      if (audiourl) {
        callurl += "&audiourl=" + encodeURIComponent(audiourl);
      }
      if (options) {
        callurl += "&options=" + encodeURIComponent(options);
      }

      if (stream) {
        this.pc.addStream(stream);
      }

      // clear early candidates
      this.earlyCandidates.length = 0;

      // create Offer
      this.pc.createOffer(this.mediaConstraints).then(
        sessionDescription => {
          // console.log("Create offer:" + JSON.stringify(sessionDescription));

          this.pc.setLocalDescription(sessionDescription).then(
            () => {
              fetch(callurl, { method: "POST", body: JSON.stringify(sessionDescription) })
                .then(this._handleHttpErrors)
                .then(response => response.json())
                .catch(error => this.onError("call " + error))
                .then(response => this.onReceiveCall(response))
                .catch(error => this.onError("call " + error));
            },
            error => {
              console.log("setLocalDescription error:" + JSON.stringify(error));
            }
          );
        },
        error => {
          alert("Create offer error:" + JSON.stringify(error));
        }
      );
    } catch (e) {
      this.disconnect();
      alert("connect error: " + e);
    }
  };
  WebRtcStreamer.prototype.getIceCandidate = function () {
    setTimeout(() => {
      fetch(this.srvurl + "/api/getIceCandidate?peerid=" + this.pc.peerid)
        .then(this._handleHttpErrors)
        .then(response => response.json())
        .then(response => this.onReceiveCandidate(response))
        .catch(error => this.onError("getIceCandidate " + error));
    }, 1000);
  };

  /*
   * create RTCPeerConnection
   */
  WebRtcStreamer.prototype.createPeerConnection = function () {
    console.log("createPeerConnection  config: " + JSON.stringify(this.pcConfig));
    this.pc = new RTCPeerConnection(this.pcConfig);
    let pc = this.pc;
    pc.peerid = Math.random();

    pc.onicecandidate = evt => this.onIceCandidate(evt);
    pc.onaddstream = evt => this.onAddStream(evt);
    pc.oniceconnectionstatechange = evt => {
      console.log("oniceconnectionstatechange  state: " + pc.iceConnectionState, evt);
      if (this.videoElement) {
        if (pc.iceConnectionState === "connected") {
          this.videoElement.style.opacity = "1.0";
        } else if (pc.iceConnectionState === "disconnected") {
          this.videoElement.style.opacity = "0.25";
        } else if (pc.iceConnectionState === "failed" || pc.iceConnectionState === "closed") {
          this.videoElement.style.opacity = "0.5";
        } else if (pc.iceConnectionState === "new") {
          this.getIceCandidate();
        }
      }
    };
    pc.ondatachannel = function (evt) {
      console.log("remote datachannel created:" + JSON.stringify(evt));

      evt.channel.onopen = function () {
        console.log("remote datachannel open");
        this.send("remote channel openned");
      };
      evt.channel.onmessage = function (event) {
        console.log("remote datachannel recv:" + JSON.stringify(event.data));
      };
    };
    pc.onicegatheringstatechange = function () {
      if (pc.iceGatheringState === "complete") {
        const recvs = pc.getReceivers();

        recvs.forEach(recv => {
          if (recv.track && recv.track.kind === "video") {
            // console.log("codecs:" + JSON.stringify(recv.getParameters().codecs));
          }
        });
      }
    };

    try {
      let dataChannel = pc.createDataChannel("ClientDataChannel");
      dataChannel.onopen = function () {
        console.log("local datachannel open");
        this.send("local channel openned");
      };
      dataChannel.onmessage = function (evt) {
        console.log("local datachannel recv:" + JSON.stringify(evt.data));
      };
    } catch (e) {
      console.log("Cannor create datachannel error: " + e);
    }

    console.log("Created RTCPeerConnnection with config: " + JSON.stringify(this.pcConfig));
    return pc;
  };
  /*
   * RTCPeerConnection IceCandidate callback
   */
  WebRtcStreamer.prototype.onIceCandidate = function (event) {
    if (event.candidate) {
      if (this.pc.currentRemoteDescription) {
        this.addIceCandidate(this.pc.peerid, event.candidate);
      } else {
        this.earlyCandidates.push(event.candidate);
      }
    } else {
      console.log("End of candidates.");
    }
  };
  WebRtcStreamer.prototype.addIceCandidate = function (peerid, candidate) {
    fetch(this.srvurl + "/api/addIceCandidate?peerid=" + peerid, { method: "POST", body: JSON.stringify(candidate) })
      .then(this._handleHttpErrors)
      .then(response => response.json())
      .then(response => {
        console.log("addIceCandidate ok:" + response);
      })
      .catch(error => this.onError("addIceCandidate " + error));
  };

  /*
   * RTCPeerConnection AddTrack callback
   */
  WebRtcStreamer.prototype.onAddStream = function (event) {
    console.log("Remote track added:" + JSON.stringify(event));

    this.videoElement.srcObject = event.stream;
    let promise = this.videoElement.play();
    if (promise !== undefined) {
      promise.catch(error => {
        console.warn("error:" + error);
        this.videoElement.setAttribute("controls", true);
      });
    }
  };

  /*
   * AJAX /call callback
   */
  WebRtcStreamer.prototype.onReceiveCall = function (dataJson) {
    // console.log("offer: " + JSON.stringify(dataJson));
    let descr = new RTCSessionDescription(dataJson);
    this.pc.setRemoteDescription(descr).then(
      () => {
        console.log("setRemoteDescription ok");
        while (this.earlyCandidates.length) {
          let candidate = this.earlyCandidates.shift();
          this.addIceCandidate(this.pc.peerid, candidate);
        }

        this.getIceCandidate();
      },
      error => {
        console.log("setRemoteDescription error:" + JSON.stringify(error));
      }
    );
  };

  /*
   * AJAX /getIceCandidate callback
   */
  WebRtcStreamer.prototype.onReceiveCandidate = function (dataJson) {
    console.log("candidate: " + JSON.stringify(dataJson));
    if (dataJson) {
      for (let i = 0; i < dataJson.length; i++) {
        let candidate = new RTCIceCandidate(dataJson[i]);

        console.log("Adding ICE candidate :" + JSON.stringify(candidate));
        this.pc.addIceCandidate(candidate).then(
          () => {
            console.log("addIceCandidate OK");
          },
          error => {
            console.log("addIceCandidate error:" + JSON.stringify(error));
          }
        );
      }
      this.pc.addIceCandidate();
    }
  };
  /*
   * AJAX callback for Error
   */
  WebRtcStreamer.prototype.onError = function (status) {
    console.log("onError:" + status);
  };

  return WebRtcStreamer;
})();

if (typeof window !== "undefined" && typeof window.document !== "undefined") {
  window.WebRtcStreamer = WebRtcStreamer;
}
if (typeof module !== "undefined" && typeof module.exports !== "undefined") {
  module.exports = WebRtcStreamer;
}
